1. Field of the Invention
The present invention relates to portable electronic devices, particularly to a portable electronic device with a hall sensor which is responsive to magnetic fields.
2. Discussion of the Related Art
With the development of wireless communication and information processing technologies, foldable electronic devices such as mobile phones and PDAs (Personal Digital Assistants) are now in widespread use, and consumers may now enjoy the full convenience of high technology products anytime and anywhere. Foldable electronic devices are particularly favored by a wide range of consumers because of their small size, novel design and ease of use.
The foldable electronic device such as mobile phone generally includes a cover section and a body section. The cover section and the body section are rotatably interconnected through a hinge assembly, thus allowing the mobile phone to be switched between an in-use position and a closed position. When the cover section is opened relative to the body section, the mobile phone is automatically switched to a work mode. Accordingly, the keypads may be operated so as to input information by user. The background lights and the liquid crystal display in the mobile phone are actuated. However, when the cover section is not fully closed relative to the body section, the liquid crystal display and the background light will be shut off.
The above function of the foldable electronic device is provided by a device controlling a main circuit to be conducted or be shut off. The device usually includes a hall sensor and a magnet. The hall sensor is a transducer, which varies output voltages in response to changes in magnetic field. Due to a change of the position relationship between the hall sensor and the magnet, the hall sensor is affected by magnetic fields of the magnet so as to activate or shut off the main circuit. Referring to FIGS. 6 and 7, a mobile phone 10 is provided. The mobile phone 10 includes a body section 12, a cover section 14 and a hinge assembly 16. The hinge assembly 16 is rotatably connected to the body section 12 and the cover section 14. The body section 12 has a printed circuit board 120 positioned therein. The printed circuit board 120 has a main circuit, and the main circuit is electronically connected to a hall sensor 122. The cover section 14 disposes a magnet 142 therein corresponding to the hall sensor 122. The magnet 142 includes an S pole 1424 and an N pole 1422. When the cover section 14 is closed relative to the body section 12, the S pole 1424 of the magnet 142 is opposite to the hall sensor 122.
When the user opens the mobile phone 10, the cover section 14 with the magnet 142 is far from the body section 12. Accordingly, the hall sensor 122 is far from the S pole 1424 of the magnet 142, and is toward the N pole 1422. The hall sensor 122 then activates the main circuit of the printed circuit board 120 so that the mobile phone 10 is switched to a work mode. The user may operate the mobile phone 10. If the cover section 14 is closed to some angles relative to the body section 12, the hall sensor 122 is turned to toward the S pole 1424 of the magnet 142. The hall sensor 122 will switch the main circuit to be shut off, and allow the mobile phone 10 to be in a power saver mode. Although the above device may realize the control for the work mode of the mobile phone, the magnet 142 will occupy a space along a thickness direction in the cover section 14. The cover section 14 requires a thin thickness, however, this structure increases the thickness of the cover section 14, and will not satisfy a development tendency of miniaturization for mobile phones.
Therefore, an improved portable electronic device for activating or shutting off the call mode is desired in order to overcome the above-described shortcoming.